The present invention relates to soldering iron tips for electric soldering tools and for desoldering tools. It further relates to methods of manufacturing soldering iron tips.
Soldering is a method for connecting and bonding components and especially in the electronics industry. Soldering can be roughly classified into two categories, namely, mass soldering (batch soldering) and manual soldering. Mass soldering includes flow soldering mounting elements or components on a printed circuit board and then immersing the board in a molten solder bath. Mass soldering further includes reflow soldering (SMT) wherein soldered particles and flux are mixed with a binder or additive to form a solder paste. The solder paste is printed on the circuit board, and the elements are then mounted on the circuit board and heated so as to solder them. Both of these methods allow simultaneous soldering of multiple points.
Manual soldering using an electric soldering iron allows generally any user to easily perform soldering operations. Manual soldering can be used following the mass soldering methods described above, to repair localized defective soldering, or to solder parts which could not be soldered with the mass soldering methods.
Conventional soldering iron tips for electric soldering irons are made of copper or copper alloys and their forward ends are iron plated with a thickness of several tens micrometers to several hundreds micrometers in order to prevent solder corrosion. This plated area is then coated with solder, and soldering operations are performed therewith. In the past it was common for the principal components of solder to be tin and lead (SN—Pb solders of which SN—Pb eutectic solder is representative thereof. However, in recent years due to environmental concerns, lead is less commonly used and so-called lead-free solders have been more frequently used. Examples of lead-free solders are SN—Cu solders, Sn—Ag solders, and Sn—Au—Cu solders.
As compared to Sn—Pb solders, it is more difficult to achieve good solder joints with lead-free solders, due to inferior solder wetting and ease of solder spreading. The primary causes of inferior solder wetting include the facts that the melting points are 20 to 45° C. higher than Sn—Pb solders and the tips of the soldering irons are more readily oxidized. Consequently, soldering work using manual soldering methods has suffered. Soldering defects are likely to result with manual soldering which uses lead-free solder and thereby more frequent repairs are required. The present applicants have invented technology for improving soldering performance while maintaining substantially the same degree of solder corrosion of the soldering iron tip as with iron plated articles. This is described in patent document A JP-2000-317629, entitled “Soldering Iron Tip” and filed on May 10, 1999, the entire contents of which are hereby incorporated by reference. As described in this document, instead of conventional iron plating, an Fe—Ni alloy plating is used at the forward end of the soldering iron tip, or an Fe—Ni alloy covering member (a bulk material) is provided to improve soldering performance.
Furthermore, soldering related operations include desoldering wherein (electric) solder suction devices are used to remove undesired solder. These devices have a suction nozzle that is heated such as by a built-in heater, and the end of the heated suction nozzle is contacted with the solder to thereby melt it. The molten solder is suctioned into the interior of the desoldering tool through an opening at the end of the suction nozzle. The suctioning is performed by a vacuum pump or the like, and the molten solder is stored in a tank (or a capsule) having a filter provided in the suction passageway thereto.
With respect to the function of melting solder when the heated tip contacts it and the requirements of good solder wetting in order to maintain good heat transfer characteristics, the suction nozzle of the electric solder suction device is similar to the soldering iron tip of an electric soldering iron, and similar iron plating is typically used at the forward end thereof. Similar to the soldering iron tip of the electric soldering iron, desoldering tip corrosion is to be prevented while maintaining solder wettability, even when using lead-free solder.